JPH05296939A - Optical disk inspecting device - Google Patents

Abstract

PURPOSE:To obtain an optical disk inspecting device which can accurately detect a defect on an optical disk even when the optical disk gently or slightly warps or waves. CONSTITUTION:When an optical disk 1 to be inspected is irradiated with inspection light 5 from a light source 4, the intensity of at least one of reflected light, scattered light, and interference light from the disk 1 is detected in two or more directions by means of optical sensors 6a and 6b. A computing element 7 calculates the detecting signals of the sensors 6a and 6b and a storage circuit 8 stores the calculated results of the element 7 as a signal pattern. A discrimination circuit 10 discriminates the presence/absence and kind of a defect on the disk 1 by comparing the signal pattern with the signal pattern of a reference optical disk having a quality to be used as a reference generated from a reference pattern generator 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk inspection apparatus for irradiating an optical disk with inspection light to judge the quality of the optical disk and analyze the manufacturing process. Related to the technology to judge properly.

[0002]

2. Description of the Related Art Generally, a track is formed on the surface of an optical disk concentrically or spirally with its rotation axis, and a laser beam is irradiated along the track from an optical head for optical recording. Alternatively, playback is performed. Therefore, in order for the optical disc as a product to be proper, the tracks need to be accurately formed. In addition, when recording and reproducing information, the laser light passes through the transparent substrate of the disc and is irradiated onto the recording surface.
If there is an obstacle inside or on the surface of this transparent substrate that obstructs or distorts the entry of laser light, correct recording or reproduction cannot be performed. Furthermore, since the optical head is arranged close to the surface of the optical disc and is moved by the drive mechanism during the recording / reproducing operation, if there is a protrusion on the surface of the optical disc, the operation of the optical head is hindered. To be done. In order to prevent such an obstacle, an optical disc inspection device for inspecting whether or not the optical disc has a defect is used.

[0003]

An optical disk made of a plastic material has a shape and optical characteristics such as warping and waviness caused by thermal strain generated during molding such as hot press molding and heat injection molding. It has an unavoidable inhomogeneity in the manufacturing process. Since such inhomogeneity is weak or gradual, it often does not cause an obstacle at the time of recording or reproducing of the apparatus. However, when inspecting using the above-mentioned optical disc inspection apparatus, there is a problem that the above-mentioned inhomogeneity becomes a disturbance on the inspection and the defect of the optical disc cannot be correctly identified due to the disturbance.

The present invention has been made in order to solve such a problem, and it is possible to reduce warpage and distortion.
Alternatively, it is another object of the present invention to provide an optical disc inspection device capable of accurately detecting a defect of an optical disc having a weak inhomogeneity.

[0005]

In order to achieve the above object, the present invention provides a light source for irradiating an optical disc to be inspected with inspection light, and a reflection light, a scattered light, and an interference light of the inspection light from the optical disc. An optical disc inspection apparatus for detecting a defect of the optical disc based on an output signal from the optical sensor, wherein the optical sensor includes the reflected light and the scattered light. A structure for detecting the intensity of at least one of the interference lights from two or more directions, a calculating means for calculating an output signal from the optical sensor, and a memory for storing a result of the calculation by the calculating means as a calculating signal. Means, a reference pattern generating means for generating a pattern of a signal output from the optical sensor when the inspection light is applied to the optical disc which is a quality reference, and the reference pattern generating means. Is obtained by a determination means for comparing the pattern of the stored the operation signal to said storage means and the generated signal pattern from chromatography emissions generating means to determine the acceptability of the quality of the test optical disk.

[0006]

With the above structure, when the inspection light is emitted from the light source to the optical disc to be inspected, the intensity of at least one of the inspection light reflected by the optical disc, scattered light, and interference light is detected by the optical sensor. Is detected from two or more directions. When the output signal of the optical sensor is input to the calculation means, the calculation means calculates the signal, the calculation result is output to the storage means as the calculation signal, and is stored as the calculation signal pattern in the storage means. Then, a signal pattern of the light intensity when the inspection light is applied to the reference optical disk having the reference quality is generated by the reference pattern generation means, and the reference signal pattern and the operation signal pattern stored in the storage means are generated. Is compared by the judging means, the presence or absence and the type of defect of the optical disc to be inspected are discriminated, and the quality of the optical disc is judged.

[0007] Usually, the defects of the optical disk are minute, and therefore the distribution of the reflected light, the scattered light, and the interference light of the inspection light when the inspection light is applied to the optical disk is known in advance. For example, when an optical sensor for detecting interference light is used as the inspection light sensor, if the track of the optical disk is damaged, the intensity of the interference light generated by the track is weakened so that Although the signal intensity of the optical sensor provided is weak, there is almost no change in the signal intensity of the optical sensor that detects the interference light in the parallel direction of the tracks. On the other hand, the inhomogeneity in the optical disc is
It is distributed over a wide range on the optical disk and changes the signal intensity of the interference light sensor arranged in the direction parallel to the track.

When an optical sensor for detecting scattered light is used and there is a protrusion-like obstacle as a defect of the optical disc, the obstacle generally has a substantially point-symmetrical shape, and therefore any direction The signal intensity changes in the scattered light sensor arranged at, but the signal intensity change due to the inhomogeneity described above appears only in the scattered light sensor disposed in a specific direction. Thus, by detecting the light from two or more directions by the optical sensor and calculating the output signal thereof, it is possible to strictly identify the defect of the optical disc.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a basic configuration diagram of an optical disc inspection apparatus according to this embodiment. In the figure, an optical disc 1 to be inspected is supported by a rotating mechanism 2 and is rotationally driven at a predetermined speed. The optical disc 1 is provided with a number of concentric circular or spiral tracks 3. And
A light source 4 is disposed above the optical disc 1 at a position facing the optical disc 1, and the optical disc 1 is irradiated with inspection light 5 from the light source 4. Further, in order to detect the light intensity of the interference light of the inspection light 5 by the optical disc 1, an optical sensor 6a is arranged in the axial direction of the optical disc 1, and an optical sensor 6b is also arranged in the radial direction of the optical disc 1.

The above two optical sensors 6a and 6b are connected to an arithmetic unit 7 (arithmetic means) that receives and outputs these output signals, and the arithmetic unit 7 further includes a memory circuit 8 (memory means).
It is connected to the. Further, in the present apparatus, a pattern of signals output from the optical sensors 6a and 6b when the inspection light 5 is applied to the reference optical disc, which is a reference for quality, that is, a reference pattern for generating the reference pattern. Generator 9
(Reference pattern generating means) is provided, and the reference pattern generator 9 and the storage circuit 8 are connected to a determination circuit 10 (determination means) for determining the quality of the optical disc 1.

The operation of the optical disc inspection apparatus having the above configuration will be described. When the inspection light 5 is emitted from the light source 2 to the optical disc 1 which is rotationally driven by the rotating mechanism 2, the interference light 11a, 11b is emitted from the optical sensor 6a, 6b.
Detected by. When this detection signal is input to the calculator 7, the two detection signals are calculated in the calculator 7, and the calculation result is input to the storage circuit 8 as a calculation signal. It is stored as a signal pattern. On the other hand, the reference pattern generator 9 generates a reference pattern serving as a quality reference. And
The judgment circuit 10 compares the signal pattern stored in the storage circuit 8 with the reference pattern to judge the quality of the optical disc 1.

In the inspection by the present apparatus, for example, when the track 3 of the optical disc 1 is damaged, the damage weakens the intensity of the interference light generated by the track 3, so that the direction perpendicular to the track 3, that is, the optical disc 1. Although the signal intensity of the optical sensor 6b arranged in the radial direction becomes weak, the signal intensity of the optical sensor 6a for detecting the interference light in the parallel direction of the tracks, that is, the axial direction of the optical disc 1 hardly changes. Further, when the optical disc 1 has inhomogeneities such as warpage and waviness, the inhomogeneities are usually distributed over a wide range on the optical disc 1, and therefore the optical sensor arranged in the direction parallel to the track 3 is used. The signal strength of 6a changes.

The presence / absence of defects and inhomogeneities in the optical disc 1 and their types cannot be discriminated by a conventional device for detecting only the light 11a in one direction as shown in FIG. 2, for example. As in the present embodiment, light 11a, 11b from two or more directions with respect to the optical disc 1 is detected by the optical sensors 6a, 6b, respectively, and the output signals are calculated to determine the presence / absence of the defect and the type of the optical disc 1. Can be strictly identified.

Although one embodiment of the present invention has been described above, the present invention is not limited to this. For example, in the above embodiment, an optical sensor for detecting interference light is used. A reflected light, a scattered light, or an optical sensor that detects them in combination may be applied according to the purpose. Further, the number of optical sensors and the location of the optical sensors can be properly set depending on the material of the optical disc to be inspected and the type of defect to be detected.

[0015]

As described above, according to the present invention, the optical disc is irradiated with the inspection light and the reflected light, the scattered light, and the interference light are detected from two or more directions. Even when there is significant inhomogeneity
The defect of the optical disc can be strictly inspected without making it a disturbance in the inspection, so that the reliability of the inspection result can be enhanced and the efficiency of the inspection work can be improved. Further, by feeding back the inspection result in the analysis of the optical disc manufacturing process, the trouble in the manufacturing process can be found and the improvement plan can be promptly performed without waste, and the quality improvement and the cost reduction can be realized.

[Brief description of drawings]

FIG. 1 is a basic configuration diagram of an optical disc inspection apparatus according to an embodiment of the present invention.

FIG. 2 is a layout diagram of optical sensors in a conventional optical disc inspection apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 optical disk 4 light source 5 inspection light 6a, 6b optical sensor 7 arithmetic unit 8 storage circuit 9 reference pattern generator 10 determination circuit

Claims (1)

[Claims] 1. A light source for irradiating an optical disc to be inspected with inspection light, and an optical sensor for detecting the intensity of at least one light of the inspection light reflected by the optical disc, scattered light, and interference light. In the optical disc inspection apparatus for detecting a defect of the optical disc based on the output signal from the optical sensor, the optical sensor sets the intensity of at least one of the reflected light, the scattered light and the interference light in two or more directions. And a storage unit for storing the result of the calculation by the calculation unit as a calculation signal, and the optical disc serving as the quality reference is irradiated with the inspection light. A reference pattern generating means for generating a pattern of a signal output from the optical sensor, a signal pattern generated by the reference pattern generating means, and the memory. An optical disc inspecting apparatus, comprising: a determination unit configured to compare a pattern of the operation signal stored in a stage to determine quality of the optical disc to be tested.